src/core/selinux-setup.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <stdio.h>
   5 #include <unistd.h>
   6
   7 #if HAVE_SELINUX
   8 #include <selinux/selinux.h>
   9 #endif
  10
  11 #include "log.h"
  12 #include "macro.h"
  13 #include "selinux-setup.h"
  14 #include "selinux-util.h"
  15 #include "string-util.h"
  16 #include "util.h"
  17
  18 #if HAVE_SELINUX
  19 _printf_(2,3)
  20 static int null_log(int type, const char *fmt, ...) {
  21         return 0;
  22 }
  23 #endif
  24
  25 int mac_selinux_setup(bool *loaded_policy) {
  26
  27 #if HAVE_SELINUX
  28         int enforce = 0;
  29         usec_t before_load, after_load;
  30         char *con;
  31         int r;
  32         static const union selinux_callback cb = {
  33                 .func_log = null_log,
  34         };
  35
  36         bool initialized = false;
  37
  38         assert(loaded_policy);
  39
  40         /* Turn off all of SELinux' own logging, we want to do that */
  41         selinux_set_callback(SELINUX_CB_LOG, cb);
  42
  43         /* Don't load policy in the initrd if we don't appear to have
  44          * it.  For the real root, we check below if we've already
  45          * loaded policy, and return gracefully.
  46          */
  47         if (in_initrd() && access(selinux_path(), F_OK) < 0)
  48                 return 0;
  49
  50         /* Already initialized by somebody else? */
  51         r = getcon_raw(&con);
  52         if (r == 0) {
  53                 initialized = !streq(con, "kernel");
  54                 freecon(con);
  55         }
  56
  57         /* Make sure we have no fds open while loading the policy and
  58          * transitioning */
  59         log_close();
  60
  61         /* Now load the policy */
  62         before_load = now(CLOCK_MONOTONIC);
  63         r = selinux_init_load_policy(&enforce);
  64         if (r == 0) {
  65                 _cleanup_(mac_selinux_freep) char *label = NULL;
  66                 char timespan[FORMAT_TIMESPAN_MAX];
  67
  68                 mac_selinux_retest();
  69
  70                 /* Transition to the new context */
  71                 r = mac_selinux_get_create_label_from_exe(SYSTEMD_BINARY_PATH, &label);
  72                 if (r < 0 || !label) {
  73                         log_open();
  74                         log_error("Failed to compute init label, ignoring.");
  75                 } else {
  76                         r = setcon_raw(label);
  77
  78                         log_open();
  79                         if (r < 0)
  80                                 log_error("Failed to transition into init label '%s', ignoring.", label);
  81                 }
  82
  83                 after_load = now(CLOCK_MONOTONIC);
  84
  85                 log_info("Successfully loaded SELinux policy in %s.",
  86                          format_timespan(timespan, sizeof(timespan), after_load - before_load, 0));
  87
  88                 *loaded_policy = true;
  89
  90         } else {
  91                 log_open();
  92
  93                 if (enforce > 0) {
  94                         if (!initialized) {
  95                                 log_emergency("Failed to load SELinux policy.");
  96                                 return -EIO;
  97                         }
  98
  99                         log_warning("Failed to load new SELinux policy. Continuing with old policy.");
 100                 } else
 101                         log_debug("Unable to load SELinux policy. Ignoring.");
 102         }
 103 #endif
 104
 105         return 0;
 106 }